The mood was upbeat, but according to some less cheerful than previous anti-Brexit marches.
As MPs debated the future of Brexit in parliament, hundreds of thousands rallied in central London waving EU flags, blue and yellow berets and placards reading "Betrayed by Brexit".
The irony was not lost on many of those attending the mammoth 'People's Vote’ rally.
Among them is Dublin native Mairead, who has lived in Warwickshire for 30 years.
"I’m asking for a second referendum," she told RTÉ News as the rally got under way.
"The Irish have stood up very well with the EU and I think Ireland is an absolute great advert for what it is to be European and I’m really proud of that."
Mairead, originally from Dublin, has lived in the UK for 30 years and is marching in the #PeoplesVoteMarch in London. She told @rtenews that Ireland is a great advert for Europe and that #brexit is dividing rather that uniting the country. pic.twitter.com/PnDeDhIoeg
— Dimitri O'Donnell (@dimitriodonnell) October 19, 2019
As the march slowly made its way from Hyde Park through central London both the crowds and the confidence of those marching grew in strength. By the time they reached Parliament Square, organisers claimed that close to one million people had turned out for the rally.
Verity Davis was one of the thousands of early risers on the streets. She got up at 5am to travel from her home in Cardiff to the capital. "I can’t allow a decision to be made like this that has such wide reaching impacts financially, economically and socially."
"It’s just too big not to try and stop it," she said as her Welsh friends and family nodded in agreement.
It’s a view shared by the majority of those who participated in the "Final Say" march on a bumper ‘Super Saturday’ in British politics.
Musician Bob Geldof also joined the crowds with his family on a sunny Saturday afternoon outside the House of Commons.
He told RTÉ News that while he supported the spirit of the march, the overall outcome could amount to nothing. "I don’t think it makes any difference," Mr Geldof said.
"There’s a very sad atmosphere. It’s very odd to feel that you are in the last days in Europe and being part of Europe is what loads of us fought to be in back in the day."
Bob Geldof left Ireland in the 1970s and he has lived in the UK ever since. He is one of many high profile celebrities backing calls for a second Brexit referendum.
Mr Geldof says he has noticed that the atmosphere in the UK has changed since the Brexit result.
"Because they’ve [British people] realised that Ireland is a separate individual country, even at the highest level, it has sort of been a shock. But there’s more rage between the Brexiteers and the Remainers - there’s real enmity."
Mr Geldof told RTÉ News he has lost friends because of his pro-Europe stance. "A friend of mine had a dinner where he toasted all his friends, they were all Leavers, and then he said this was the last time I will ever see you again and that is very sad."
As Mr Geldof left the people’s vote rally, he felt the wrath of Brexiteers. He was called a "traitor" by some who blamed him and other Remainers for the latest Brexit delay.
There were huge cheers as the results of the Letwin amendment was announced on a big screen in the square.
The massive crowds revelled in the carnival-like atmosphere outside parliament.
Former Downing Street Press Secretary Alistair Campbell said the rallies have brought about real change. "For the first marches we couldn’t get more than a few thousand to turn up, we couldn’t get MPs to speak at them. It was a real struggle to get them going," he told RTÉ News.
"This [march] is big and the last one was big and they do make a difference and you can’t quantify that difference," he added.
As the Remainers left with big smiles on their faces the mood inside parliament was not as rosy.
Emboldened by the success of their latest campaign the organisers have not ruled out further rallies as the uncertainty continues.
